Ink order for 4 colour process...

[fireplug55]

Back trap from the high volume of Cyan and Magenta and minimal Yellow.
Reduce the Yellow ink and possibly add take off bars to the Yellow plate to allow more ink coverage. This will help with the back trap issue.

 

[john beniston]

The only thing i can think of is that roller cooling might be a problem with the black down last. You will have to reset all the roller temperatures if you 're using different temp's for each colour.
If you are using max black or GCR separations then black down last might well be preferable.
The magenta on cyan, yellow on cyan, and yellow on magenta trapping should stay the same because that part of the sequence is still the same as normal.

 

[Disappointed]

Back trap from the high volume of Cyan and Magenta and minimal Yellow.
Reduce the Yellow ink and possibly add take off bars to the Yellow plate to allow more ink coverage. This will help with the back trap issue.

I tried adding some take-off stripes and bars today as we were going to be running troublesome stock all day. We managed to get a 10mm stripe down each side and a 5mm one across the back edge.

I have just finished running for the day, 12 jobs done and the yellow ink is as fresh as it was this morning, not a hint of back-tracking, I am amazed as we have never had yellow stay this clean on this stock. The jobs look a bit funky but the result speaks for itself. Yellow ink usage was actually lower than before as although I was running more image area, I didn't have to keep scraping it out the ends of the duct and binning it all day.

We will stick with this for a while I think.

Thanks for the suggestion.

 

[jbeniston]

The setup - B3 Waterless Offset machine.

Can anyone tell me why I should not alter my ink order from K-C-M-Y to Y-M-C-K??

What are the possible side effects of doing so?

Is there a specific reason for running K-C-M-Y?


Many thanks


Dave

The rule of thumb regarding printing sequence is to put the lightest weight image down first which is normally black, getting progressively heavier as you go.
If you are using GCR or MaxBlack the black will have the most image so it can go down last. Lots of web guys do this. Otherwise KCMY is the way to go. Talk to the pre press guys and find out if you use GCR or MaxBlack.

 

[Disappointed]

The rule of thumb regarding printing sequence is to put the lightest weight image down first which is normally black, getting progressively heavier as you go.
If you are using GCR or MaxBlack the black will have the most image so it can go down last. Lots of web guys do this. Otherwise KCMY is the way to go. Talk to the pre press guys and find out if you use GCR or MaxBlack.

No need now, we are getting good results running K-M-C-Y

 

[gordo]

No need now, we are getting good results running K-M-C-Y

If that's correct then there's a good chance that something is wrong somewhere in your process.
Just sayin'.

gordo

 

[Disappointed]

If that's correct then there's a good chance that something is wrong somewhere in your process.
Just sayin'.

gordo

Yes, we know.
We are running waterless and finding a good ink that is also ISO standard hue is next to impossible. We are testing a new mix on behalf of Van-Son and it's nearly there, just the yellow is slightly too tacky which causes duct contamination on low coverage jobs.

Running the revised colour order has stopped the magenta tracking back but left a lesser problem of cyan tracking. Running the take-off bars to increase the ink flow has completely stopped all contamination.

Hopefully Van-Son will be able to formulate-out the remaining issues and we will be left with an excellent ink at last.

One of the few problems with waterless offest i guess.

 

[Disappointed]

UPDATE

Following on from the trials we undertook in conjunction with Van-Son and Presstek, We now have a totally new ink formulation to use, Presstek are marketing it as "Di-Envi" waterless ink.

It came in back in November and we have been running it since then with near perfect results, it's now duct-fresh, rapid drying on the sheet, good gloss, perfect match for ISO 12647 on most stocks, and with the addition of small take-off bars on the yellow, will run all day without contamination in the yellow.

We are still running K-M-C-Y as that seems to give us the best results on purples etc. I might try switching back one day when I get some time.

Try as hard as i may but I have not been able to get this ink to tone on the press yet, fast, slow, light, heavy, hot, cold, whatever. We are running at 23c on the rollers and it gives great results at that temperature.

Seems to be good stuff.

 

[D Ink Man]

Congratulations sir, I hope it has staying power for you in the long run.

As far as running K-M-C-Y don't worry about it one iota, regardless of what someone says. You are getting very good results after many trials and tribulations and are succeeding. This is what is important and not being gilded by texts of proper offset rotations and such. You are intelligent, a craftsman and found the way via means of dilligence and art. That's what lithography is! D

 

[gordo]

Congratulations sir, I hope it has staying power for you in the long run.

As far as running K-M-C-Y don't worry about it one iota, regardless of what someone says. You are getting very good results after many trials and tribulations and are succeeding. This is what is important and not being gilded by texts of proper offset rotations and such. You are intelligent, a craftsman and found the way via means of dilligence and art. That's what lithography is! D

Printers can use whatever ink rotation their hearts desire, however, if They are targetting their presswork to an industry standard print characteristic that is based on data derived from a certain ink rotation then, IMHO, there is something wrong in the process if you do not follow that same ink rotation and I would question the kevel of success.

You are intelligent, a craftsman and found the way via means of dilligence and art. That's what lithography is! D

I couldn't agree less.

Gordo

 

[D Ink Man]

Printers can use whatever ink rotation their hearts desire, however, if They are targetting their presswork to an industry standard print characteristic that is based on data derived from a certain ink rotation then, IMHO, there is something wrong in the process if you do not follow that same ink rotation and I would question the kevel of success.



I couldn't agree less.

Gordo

Gordo is the God of Printing. Everyone should agree.

 

[gordo]

Gordo is the God of Printing. Everyone should agree.

On that, again, I couldn't disagree with you more.

G

 

[Disappointed]

Come on now you guys, shake and make up

I fully understand Gordon's point of view though but as the results do indeed speak volumes, we will be staying with the revised order for the current time at least. Obviously there is something odd going on but, as we are battling the problem in a waterless environment, which ISO12647 was not invented for, I believe we can make variations as we desire as long as the results are good, and they are good.

Would I buy waterless again, hmm, tough question but I would likely say no, but only because I believe the future is in sheet-fed ink-jet technology, I have been saying that for some years and the dream is now becoming reality.

As it stands, our press is a beautiful bit of kit, it's small, fast, clean, very quick to turn round jobs, and so-far has been very reliable. Not having to worry about ink-water balance is a luxury, although there are caveats to that but overall it is a good press and the print quality is second to none.

Happy days. (but I still miss the old Solna 124)

 

[kjp17]

KMCY or KCMY.

 

[john beniston]

You should always run from the lowest area coverage (black) to the highest(yellow)
Trapping will be an issue, you will be printing cyan over yellow and magenta over yellow and cyan over magenta. I do not think that the secondary pigment colours red, green, blue, will be anywhere close to where they should be.